Basic parameters at an air-interface physical layer in a long term evolution (LTE for short) system are mostly constant. For example, a subcarrier spacing is 15 KHz, a length of a transmission time interval (TTI for short) is 1 ms, and a quantity of symbols in a timeslot is seven orthogonal frequency division multiplexing (OFDM for short) symbols. Most parameters in the LIE system are not adjusted dynamically. A base station in the LIE system sends a data transport block (TB for short) to user equipment LE by using a physical downlink shared channel (PDSCH for short). Currently, a modulation and coding scheme for the PDSCH is Turbo coding. After detecting data transmission over the PDSCH, a terminal device feeds back information about a hybrid automatic repeat request—acknowledgment (HARQ-ACK for short) to the base station by using a physical uplink control channel (PUCCH for short). The HARQ-ACK may be an acknowledgment (ACK for short) or a negative acknowledgment (NACK for short), that is, an ACK/NACK response.
Currently, a coding method for a downlink shared channel (DL-SCH for short) and an uplink shared channel (UL-SCH for short) of a data transmission service in LTE is Turbo coding. Coding and modulation schemes for these channel types are all corresponding to Turbo codes. An input bit length of a Turbo-code encoder ranges from 40 bits to 6144 bits. For a data service less than 40 bits, that is, a small data packet, Turbo codes are inapplicable because of relatively poor performance.
In addition, LTE uses a fixed frame structure, for example, a fixed subcarrier spacing, a fixed TTI length, a fixed quantity of symbols, a fixed cyclic prefix (CP for short) configuration, and other fixed parameters; feedback information sent by a corresponding terminal device has a fixed feedback delay, and the feedback delay is at least 4 ms. When a low-delay type service in a communications system requires that a delay be less than 4 ms, a method in which a fixed frame structure is used for data transmission is inapplicable.
It can be learnt that a main configuration of a service channel in a current LTE system is fixed and cannot meet requirements of different services or scenarios.